DEVELOPMENT OF A COLORED BELLEEK 

BODY 



HAROLD THORNTON GOSS 



THESIS 

FOR THE 

DEGREE OF BACHELOR OF SCIENCE 

IN 

CERAMIC ENGINEERING 



COLLEGE OF ENGINEERING 
UNIVERSITY OF ILLINOIS 



1922 



!Z 5, 



}^ 2 ^ 

Caa 

< 

H 

ns 

CL 



UNIVERSITY OF ILLINOIS 



Tune... .3. 



THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY 

Harold Thornton Coss 

"THT BRVRLOPMRNT OP A COLORBO BRLLRRK BODY" 

ENTITLED 



IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE 
DEGREE OF £.a.aMl.or ...Qf .. Sc? i.ence 






Digitized by the Internet Archive 
in 2015 



https://archive.org/details/developmentofcolOOcoss 



TABLE OF CONTENTS 



Page 

I . INTRODUCTION 1 

II. GENERAL FIELD TO BE COVERED 2 

III. EXPERIMENTAL PROCEEDURE FOR BODE 7 

Materials Used 7 

Development of the Fritt 8 

Development of the Body 11 

Burning 15 

Properties of the Burned Ware 16 

Selection of the Best Body 18 

IV. EXPERIMENTAL PROCEEDURE FOR COLOR 19 

Casting Properties 21 

Burning 22 

Properties of the Burned Ware 22 

Deformations 24 

V. SUMMARY OF RESULTS 24 

VI. GENERAL CONCLUSIONS 24 

VII. ACKNOWLEDGEMENT 25 






. 






. 









. 












. 

. 






























THE DEVELOPMENT OP A COLORED 



BELLEEK BODY". 

I. INTRODUCTION. 

A belleek body i3 one of the mysteries of modern Ceramics. 
Although the general properties of the burned body are known, and 
the beauty and value of the delicate creamy ware made from it are 
fully appreciated , there i3 no authoritative data nor literature 
available on the subject. We know it was first developed by Mr. 
Armstrong and Mr^McBirney in 1863 in the little town of Belleek, 
County Parmanagh, Ire land, and that a factory was started there. 

Prom this factory came the first belleek ware.(l) A Mr. Bromley 
was engaged from Stoke-on-Trent , and he succeeded in putting the 
pottery on a commercial basis. In 1883 Mr. Bromley came to America 
and eventually assisted Mr. J.H. Brewer in hi3 development of bell- 
eek at Trenton ,N. J. Prom the old Ott and Brewer pottery has grown 
the Lennox , Incorporated .which is the only firm in the world at 
present making belleek which rivals the original. Mr.McBirney die d 
in 1884 and his partner shortly after. (2) The quality of the ware 
quickly degenerated , and although the original factory is still in 
existence , and makes parian v/are.the product i3 not to be compared 
with the early belleek. The secrets of the methods and materials 
are confined to the Lennox , Incorporated , alone. The original secrets 
died with the belleek founders. 

Prom occasional discussions in the Transactions of the 
American Ceramic Society by Professor Binns and Professor Purdy, 
we have our only technical literature on the subject. 



(1' '*Ce r amic Art in Great Britain" .L. -Jewitt. Pp. 601-609: 
(j?)" 19 th Century English Ceramic Art" .Blacker .Pp. 476-481. 




2 

From these discussions /are find that belleek, first of all, must 
have a high degree of translucency j that it must permit of cast- 
ing and jigger ing into thin wares* that it must have lo- drying 
and burning shrinkage , and that the burned body must be "free 
from color". (3) Further than this, the belleek must be ground 
very fine in a ball mill, a point highly essential to the work- 
ing of the clay and the clarity o r the body; the body must be low 
in flint and high in feldspar, md it must be vitrified either 
in bisque or gloss. It is glazed with a fritted lead boracic acid 
glaze at Cones 1 to 3, which is four or more cones lower than 
the biscuit firing. The glaze and biscuit should be cooled 
quickly, for when cooled slowly there is a tendency for the body 
to blister and turn blue, and for the glaze to pinhole. (4) 

The above information has been included simply to show 
how scanty the knowledge 0 * belleek is. From this, it is very 
evident that prior to developing a color in belleek, it is of 
prime importance to develop a satisfactory belleek. To this end, 
a field was laid out and fully investigated. 

II. THE GENERAL FIELD TO BE COVERED. 

By a very roundabout way, a formula came into the writers 
hands, this formula purporting to be the accurate formula of 
belleek. Its authoritativeness i3 quest ionable , but Professor Binns 
corroborated the field it represents as being representative o p 
true belleek. Accordingly , with this formula as a base, a field 
was laid out, both for fritt and for body. 

(3) Transactions American Ceramic Society. Vcl . 13 , p. 86 . 

(4) Transactions American Ceramic Society. Vol.2 ,p.l85. 

























. • 



















- 















. 
















































M | 


















, . 



















































3 



The formula: 
Br itt 



Batch 



Thite glass sand 


55 


It). 


Feldspar 


34 


lh. 


Potassium carbonate 


1C 


lb. 



Britt 


20 


lh. 


Calcined feldspar 


64 


lh. 


China clay 


60 


lh. 



Golding No.l 40 

National 20 

The ceramic formula for this hody is 
Britt K g O 

2 .64 



Al 2°3 



Si 0 2 
21.3 



Body 



X p 0 
.4 09 



Al^O 



3 



Si 0 p 
3.935 



The field laid out and investigated is indicated on the 
two triaxial diagrams following. 



Po+assi u m Carbonate Feldspar 



4 




<T> 



Cj 

ft' 

*o 

«/> 

<-0 

ft 

Sc 



Field of Ffitt 



5 












6 




Batch weights 


of fritt, from Triaxial Diagram 




Fritt body no. 


Sand 


Potassium carbonate 


Feldspar 


A 




60 


15 


25 


B 




So 


10 


30 


C 




60 


5 


35 


D 




50 


15 


35 






50 


10 


5 


F 




50 


5 


45 


G 




40 


15 - 


45 


H 




40 


10 


5 0 


I 




40 


5 


55 


Batch weights 


of body, 


from Triaxial Diagram 




Body no. 


Feldspar 


Fritt 


H. and G.A1 N.Ca. 


Fla. 


1 


40 


25 


23 6 


6 


2 


30 


25 


30 7 .5 


7 .5 


3 


30 


15 


23 6 


6 


4 


40 


15 


30 7 .5 


? .5 


5 


30 


15 


36 9 . 16 


9 . 16 


6 


60 


5 


23 6 


6 


7 


5 0 


5 


30 7 .5 


7 .5 


a 


40 


5 


36.6 9.16 


9 . 16 


9 


30 


5 


43.4 10.8 


1C .8 


When the 


"body with the 


best pr 


operties and the appearance 


most typical 


of belleek wa 


s determined, a large batch of 


it was 


made up, and 


to this coloring stain 


s were added. Two colo 


rs were 


desired , pale 


pink and pale 


green . 







7 



III. FXPFRTMFNTAL PROCFFBURF FOR THF BOW. 

Materials Used 

Feldspar was the most important ingredient. Abingdon 
feldspar was used because it was the onhr kind available. In order 
to make it easier to grind.it was calcined in:,open saggers at 
Cone two. Before calcining.it was a creamy yellow color, and after 
calcining a very light pink. 

The silica was introduced as white glass sand from Ottowa 
Illinois. This was very finely ground, and in a purer state than 
flint. According to Professor Binns it is easier to mix than flint 
when used on a commercial scale. 

The potassium carbonate used wa3 of U.S.P. quality. It is 
readily obtainable in a pure state, and is cheaper than equivalent 
amounts of other potassium salts. 

Hammil and Gillespie A 1 clay was U3ed instead of Golding 
No . 1 .because the latter is not qn the market, and the former clay 
gives a good white color, with a clear translucency . 

A combination of equal parts of Florida and North Carolina 
kaolins also gives a good white color, and the plasticity is much 
better than when either is used alone. The combination was sub- 
stituted for the National clay, now unavailable. ( 5 ) 



(5) Transactions American Ceramic Society. Vol. 18, p. 621. 



8 



Development of the Bkitt. 

Before experimenting , it was not known what effect var- 
iations in the fritt composition would have on the hody. Aside 
from this, the ease of grinding, and the solubility were other 
points to be considered. The ease of grinding obviously affects 
the properties of the body with regard to its commercial prep- 
aration. The solubility affects the properties of the casting 
slip. 

Determination of the Sintering Temperature. The fritt 
extremes A,C,G,and I were investigated for the temperature desir- 
able for fritting. (it should be noted that no distinction is made 
between the terms fritting and sintering in the discussion. In 
the term fritt is included the fritted or sintered mixture of 
materials whose batch weights are given in the table on page 6. ) 
Accordingly, the potassium carbonate was dissolved in hot water, 
one gram of potassium carbonate to two and one half cubic cent- 
imeters of distilled water. The sand and feldspar were thoroughly 
mixed by sieving and then rolling intimately on oil-cloth , after 
which the salt solution was added, and the mixture stirred. After 
drying, the mixture was introduce:' into fire .clay' fritt crucibles 
which had been prepared in the following manner. The inside of 
the crucible was dampened and a powdered calcined flint coating 
was applied. Then, a cone shaped piece of paper was inserted, and 
the fritt batch dumped into the cone, after which the paper was 
withdrawn. This effectively prevented sticking of the fritt to 
the crucible or flint, and hence the crucible could be used re- 
peatedly, a3 the fritt shrank from the flint lining, and could be 
easily removed by inverting the crucible. 



9 



The fritts were fired in a fritt furnace which was huilt 
up of compartments , each similar to a gas pot furnace. The fuel was 
gas and air. By careful attent ion , the atmosphere was kept oxidiz- 
ing. Although at first trouble was experienced in fusing the out- 
side of the fritt and only barely sintering the center core, by 
slower heating up , conditions were adjusted to secure uniformity. 

At Cone 010, none of the fritts wase sintered. They appear- 
ed 3 imply dried out. 

At Cone 05 .sintering had barely started, but the mass was 
always of a dirty gray color , indicating incomplete combustion of 
the carbon, or incomplete oxidation. 

At Cone 03, sintering had well begun. 

At Cone 00, G and I were half sintered and hal" fused. 

At Cone 1,A and C were half sintered and half fused. 

At Cone 5 , all were fused. 

At Cone 10, a milky white .homogeneous fritt was obtained. 
This was very hard to break up, and hard to grind. 

Cone 1 was the best temperature for treating mixtures 
G and I as this gave sinters which ground easily, yet were clean 
and white. 



Cone 3 was best for mixtures A and C for the same reason. 
These cones represented about the only conditions at which sat- 
isfactory results could be obtained. Accordingly , the fritts were 
fritted as follows :- 



Mixtures A,B,C 


Cone 


1 


D,E,F 


Cone 


01 


G,K,I 


Cone 


02 



In no case were they cooled by immersion in water, as this would 













■■ . 

























































10 



have washed out any soluble portions. 

Determination of the Solubilities. (6) For determining the 
solubilities , the specimens were ground , thoroughly mixed, and 
sieved between five and ten mesh. That which remained in the ten 
mesh was of such a size that the surface exposed was practically 

f 

constant. The quantity used was five grams. This was put in a 
mason jar with three hundred and fifty cubic centimeters of dis- 
tilled water. The jars were placed in a shaking machine making 
twenty one R.P.M. They were agito.ted for twenty four hours, No 
all owan c e was made for the influence of room temperature. After 
a few hours, the water showed a very slight turbidity , evidently 
due to the colloidal silicic acid which had been shaken out. 

After twenty four hours, the supernatant liquid was carefully 
decanted off and filtered through hardened filter paper. From the 
clear f iltrate , fifty cubic 'centimeters was removed , evaporated to 



drynes 


s , and weighed. 












■ Res 


ults 






Fr itt 


Cone 


Color 


Condition 


Slaking Test 


olubility 


A 


1 


Thite 


Semi-fused 


Slightly turbid 


4.2 % 


B 


1 


Wh i t e 


Semi-fused 


Cloudy 


7 .0 


C 


Jm 


White 


Sintered 


Milky white 


7.0 


D 


01 


Gray 


Semi -fused 


Slightly turbid 


9 .8 


E 


01 


Cream 


Semi-fused 


Fairly clear 


4 .9 


F 


01 


White 


Sintered 


Cloudy 


11.4 


G 


02 


Gray 


Semi-fused 


Slightly turbid 


7 . 0 


H 


02 


Cream 


Semi-fused 


Slightly turbid 


3 .5 


I 


OP. 


Wh i t e 


S intered 


Milky white 


12.2 




(6) Journal 


American Ceramic Society^ y 0 i. 3-1^20. 


P 15 3. 



11 



From the above table it can be seen that the refractor- 
iness increases with increase in potassium carbonate content. 
From the work done.it cannot be said just how much the condit- 
ion of fusion or the amount of potassium carbonate alone, affect 
the solubility, ’'here temperature conditions were the same, and 
the potassium carbonate wa-, present in smallest amount, the 
material had only sintered, was most refractory , and had the 
highest solubility. Probably if the fritt with high potassium 
carbonate content had only been sintered, its solubility would 
have been higher. The fritts were used in the condition des- 
cribed above. 

Development of the Body. 

The body was prepared especially for casting. As grind- 
ing was by far the most important feature in connection with the 
preparation , care was taken that the grinding was standardized 
and sufficient. Four ball mills having one and one half kilo- 
grams capacity each, with 3/4 inch flint pebbles to a depth of 
two and one fourth inches, were taken. All bodies having the same 
fritt composition were weighed out according to their numbers 
and positions on the triaxial diagrams. The extremes of each bod- 
y of similar fritt composition were added to + he ball mills. 

For example, the whole series of nine bodies was made up with the 
fritt A, then the whole series with the fritt B,etc. 

Bodies 1 and 2 were prepared in quantities of 9^5 grams 
each , a:^d bodies 6 and 9 of 12GC grams each. For bodies 1 and 2, 

6 15 grams of distilled water were added, which made the specific 
gravity of the resulting slip equal to 1.6 . For bodies 6 and 9, 
790 grams of water was added, which also made the slip spec- 



12 

ific gravity equal to 1.6. The correct specific gravity was chosen 
as 1.6, for on investigating , less water made the slip so heavy that 
it lumped in the mould, and more made it so thin that it cast 
slowly, and tended to crack in drying. 

The hall mills were put on the mill racks and run for 7 2 
hours at 74 R.P.M. .making a total Of 319,680 Revolutions , per charge- 
This consumed a considerable amount of time. However, the resulting 
slip ran through a 150 mesh sieve like ' r ater,and was so fine no 
grit could he found with the tongue. After each extreme was ob- 
tained, the dry weight per fifty grams of slip was determined , and 
the extremes were wet blended to secure the intermediate bodies, 
numbers 3, 4, 5 , n and 8. The bodies were then cast into trial pieces- 
in plaster moulds. The moulds were provided with a rectangular 
depression two centimeters deep, ten by five centimeters at the 
bottom, and with sides inclined outward at an angle of(lO) ten 
degrees from the vertical. A portion of each extreme was made up 
into cones. 

Properties of the Casting Slips. 

Bodies with fritt 

A 5 , 6 , 7, 8 , 9 settled quickly and collected in the 

bottom of the receptacles on standing. 5,8,9, 
were the worst in this regard. The casting conduct 
was good. Drying was rapid. 5,6,^, showed a tend- 
ency to crack at the corners. 

B This class was much better. It did not te^d to 

f flocculate or settle.it dried rapidly, did not 
crack at all in drying, and was extremely tough 
when plastic. 



13 



Bodies with fritt 

C These cast very well and were fairly strong in the 

dry state. There was some tendency to f flocculation , 
especially with the high spar bodies. 

I> This group gave trouble in casting. It cracked 

badly, no matter what consistency the slip was made. 
1,3, 4, 5 were especially bad. 5, 8, 9, or the high 
clay bodies, were fairly good. All showed a tendency 
to settle, the same as did A. 

E This group cast excellently. Number 4 was perfect 

in casting and drying conduct. With the exception 
of number 3 ,all dried safely , without cracking. 

The slip showed no tendency to fflocculate. 

E This series behaved the same as C. 

G This class was impossible to cast. Number 6 , par- 

ticularly , settled in granular form, making a uniform 
casting slip with it impossible without other 
electrolyte. All bodie3 cracked during drying, 
number 5 being the only one not to break . 

H All this group showed good casting and drying 

properties . The general behaviour was the same as 
for series B and E. 

I This group behaved similarly to C and E. There was 

tendency to crack in drying. All of the bodies 
except t-ose of high clay content , se ' tied in a 
jellylike mass very quickly. 

In addition to the above , it is significant that all 

the bodies of high potassium carbonate content formed a brown 



14 



scum on the surface of the piece when drying. When thoroughly dried 
the surface became slick, and could be peeled off. This slick scum 
was probably a form of potassium silicate. (7) 

After six or seven casts per mould with the bodies in 
series A,D,or G (the high potassium carbonate bodies), a scum 
formed on the surface of the moulds , which, rendered the latter use- 
less for further work. 

Those with medium potassium carbonate in the fritt were the 



best in casting and drying conduct. 









Dry ing 


Shrinkages . 










Note- "he 


original length pe 


r piece was ten centime 


ters. 








Fritt 


1 


2 


3 


Body 

4 5 6 


7 




8 


9 


A 


9 .7 






9.8 9.8 9.8 


9 .7 




9 .8 


9 .9 


B 


9 .7 


9 .8 


9.7 


9 .7 


9 .6 




9 .6 


9 .6 


C 


9.7 


9 .6 


9 .5 


9 .7 9 .6 9 .6 


9 .7 






9 .7 


D 


9 .8 


9 .7 




9.7 9.8 


S .8 




9.7 




E 


9 .8 


9 .5 




9.5 9.8 9.6 


9.7 




3 .6 


9 .6 


F 


9 .6 


9 .6 


9 .5 


9 .7 9 .5 9 .6 


9 .6 




9.4 


9 .5 


G 


















H 


9.7 


9 .6 


9 .6 


9 .5 9 .5 9 .7 


9 .5 




9 .4 


9 .6 


I 


9 .8 


9 .8 


9 .6 


9.7 9.5 9 .6 


9.7 




9 .6 


9 .5 


Those not 


given indicate pieces which would 


not 


dry safely. 


Shrinkage 


on the 


average amounted to 3 % .with 5 and 


6 % 


in 


the 




case of high clay, and 


2 % in 


the case of high fritt 


content 


. The 




color of 


the slip 


was 


a cream color, except the high 


feldspar bod 


y . 


which was 


pink. After 


drying 


, all were white. 











(7) Journal American Chemical Society ,1917. 
Vol. 39. Pp, 1173-1229. 



15 

Burning 

The cones made from the "body extremes were set in cone pats 
with standard cones and fired from cones five to ten. At cone five, 
vitrification was well Begun, and at cone twelve, none of the trials 
had melted , indicat ing a wide safe temperature range. 

The pieces were set in powdered calcined flint in "biscuit 
saggers. The saggers were wadded and placed in one of the coal 
fired test kilns. The kiln was fired to cone six in thirty hours. 
The cone reached in the top courses of saggers was cone six. In 
the hottm courses, cone five was reached. The fire boxes were then 
opened wide and full draft was turned on, in order to facilitate 
cooling. 

The Properties of the Burned Ware. 

After cooling, the saggers were unloaded and the flint was 
brushed from the pieces. The bodies showed the following proper- 
ties. 

Bodies A,D,and G were white, not translucent , and not thor- 
oughly vitrified. They had not deformed to that extent reached by 
some of the other bodies. The classes thus represented by their 
fritt compositions were generally unsatisfactory in their casting 
and drying conduct , also . 

■The bodies with F and I fritt composition were somewhat 
similar to A,D,and G. 

The bodies which cast well, were thoroughly vitrified , and 
held their shape, were B3 ,B 7 , Cl , C4 , and CS. The very best appearance 
was made by E4,but this showed high total shrinkage. 

The bodies with E and H fritts had excellent properties 
generally , but showed high shrinkage and deformation. 



16 



The colors varied as follows, 

Bodies with fritt A were white with a creamy tint , especial- 
ly number 1, varying to a grayish white at numbers 5 and 9. Number 
6 was perfectly white. 

Bodies with fritt B were white, except bodies 1 , 3 , 6, and 7 , 
which were white with a delicate creamy tint. 

Bodies with fritt C were white. Numbers 5, 8, and 9 showed 
the creamy tint. 

Bodies with fritt "D were all perfectly white. 

Bodies with fritt E all showed the faint creamy tint. 

The tint was especially pronounced in numbers 1,3, and 6 . 

Bodies with fritt E varied from a grayish to a creamy white 
while 5, 8, and 9 were perfectly white. 

Bodies with fritt G were all perfectly white. 

Bodies with fritt H were identical with E. 

Bodies with fritt I were identical with E. 

The translucency was not measured accurately , as the pieces 
were of relatively , but not exactly, the same thickness. Those 
showing the very best translucency were bodies E4 , E5 , e 6 , and E7 ; 

B3 and E7; Cl , C4 , and C6. Tne remainder were translucent when thor- 
oughly vitrified , but not as much so as the above. It can thus be 
seen that the bodies with high spar or medium high spar and high 
fritt content were most translucent .while the high clay bodies 
were the reverse. The triaxial diagram on the next page shows this 
more clearly. 

The deformation was not measured exactly. Most of the piec- 
es which were translucent and thoroughly vitrified .however , showed 
a tendency to draw up slightly at the ends. This was no doubt due 
partially to the method of setting. 



tr.u Clou 



n 




18 



Burning Shrinkages 



Hote- 


•The 


following 


data 


gives 


centimeters of 


length. 


The oricr- 


inal length 


per piece 


was 


ten centimeters. 








Britt 






Body 












1 


2 


3 ') 


4 


5 


6 


7 


8 9 


A 


8 -5 




8.4 


8.4 


8.4 




8.5 


8.6 


B 


8.3 


8.5 


8.4 






8.3 


8.3 


8.5 


C 


8.3 


8.3 


8.2 


8.3 


8.2 


8.3 


8.3 


8.5 


D 








8.4 






8.6 


8.6 


E 


8.1 


8.1 




8.0 


8.2 


8.2 


8.2 


8.0 8.3 


F 


8.1 


8.1 


7.9 


8.2 


8.2 


8.0 


8.2 


8.2 8.5 


H 

TV 


8.0 


8 . 1 


8.0 


7.9 


8.2 


8.1 


8.0 


8.2 8.3 


G 

I 


8.1 


8.1 


8.2 


8.2 


8.1 


8.3 




8.3 8.5 



The bodies with high clay and high potassium carbonate 
content in the fritt showed the least shrinkage. The high fritt 
content bodies showed the most shrinkage. The average burning 
shrinkage was eleven percent .making the total shrinkage fourteen 
percent . 

Selection of the Best Body. 

The body number B 7 was selected as being the most 
suitable body to represent the field because it most closely re- 
embled true belleek in appearance. It had excellent casting and 
drying conduct, very high translucency , low deformation , and good 
vitrification. In addition.it had the lowest total shrinkage cor- 
responding to the above properties , and was composed of a low 
amount of fritt, which would make it economical , to prepare on a 
commercial scale. 










I 












19 



IV. EXPERIMENTAL PROCEEDURE EOR THE COLOR. 

Realizing that pale pink and pale green are two of the 
most attractive colors when incorporated in a body, as for example, 
in jaspar .they were chosen as the color to he obtained in the 
belleek body. 

The body number B 7 was made up in quantity .and ground 
as before into slip at 1.6 specific gravity. To this body, the 
coloring was added in proportions of three percent and ten percent 
of the body weight. 

Pale pink is a difficult color to obtain at any time. ( 8) 
However, a reference was found which gave the following formula as 
one which would give a light pink in a parian body at Cone eleven. 
This stain was not fritted before incorporation in the body. 

Stain A formula 

1 

90 



Fe 0 

2 3 



Al 2°3 

Cr 0 9 

2 3 

Another formula for a light pink (9) was 
Stain B formula 

Sn0 o 149 



SiOg 

Cr 2 0 3 

CaO 



60 



.76 



112 



This calcined at Cone five in a fritt crucible in a gas pot furn- 
ace, and gave a pinkish purple color. This stain was given by Mr. 
Purdy as an underglaze pink, but it was thought probable that it 
would give the same color in the body. 

(8) Transactions American Ceramic Society. Vol. 15 »P . 14 1 . 



(9) Transactions American Ceramic Society. Vol.H,P-838 



20 



Pale green is not so difficult to obtain a3 pale pink, and 
more formulas are available. The following two formulas were 
selected as the "best. 

Stain C (1C) is given as a victoria green underglaze 
stain for U3e at from cones three to five. Accordingly , the stain 
was calcined at cone four in a method similar to that U3ed for 
stain B. 



Stain C formula 



Cr 2°3 


18.6 


Niter 


24 .7 


Flint 


ro 

o 

o 


Fluorspar 


11.0 


Whiting 


22.0 


CaS0 4 


11.0 



This gave a bright victoria green calcine. 

Stain D (4) is given as an underglaze color pale green for 
use on a body at cone six. The stain was prepared and calcined at 
cone five in a fritt crucible the same as Stain B. 



) formula 




CaO 


26 .0 


Cr 2°3 


11.4 


Sn°g 


149 


Sl0 2 


60 



This stain gave a good pale green color after the calcination. 



( 10) Transactions American Ceramic Society. Vol . 14 , P.430 . 

(11) Transactions American Ceramic Society. Vol. 11 , P.238. 



21 



The calcined stains were all ground in small color mill 3 to 
an .impalpable fineness. Then they were added to the body in portions 
of three and ten percent. The body with the stain added was mixed, 
readjusted with water to 1.6 specific gravity, and run on the ball 
mills for twenty four hours more, which mixed the color and body 
thoroughly , as well as additionally ground the color. 

The colored bodies were then cast in newly made plaster 
moulds of the same shape and size a3 was used previously for the 
body. 

Casting Properties. 

The colored body A cast excellently , dried without cracking, 
smoothly and uniformly , and did not harm the mould in the least. 

The body B al30 cast well, and dried without diff iculty ,but 
there was some firring on the mold with the high color content. 

The body C.with three percent color, cast excellently , but 
with ten percent color it tended to crack. However this proved 
wholly unsat isf actory for it not only firred the mold, but gave a 
greenish yellow stain to the mold for a depth of three fourths 
of an inch. In addition the color was unstable and rose to the top 
edges of the piece. This might have been obviated if the color 
stain had been well washed prior to its introduction in the body. 

The body D cast well with the low color content,but with the 
high color content it showed a tendency to crack, and the whole 
piece generally broke before it could be removed from the mould. 

Hone of the pieces deformed during drying. 

Cone trials and deformation bars were made from each body. 

The deformation bars were eight centimeters long, with triangular 
cross section seven tenths centimeters high. 


















. 










































































22 



Drying Shrinkages. 



Body 


Amt . Stain 


% 


Amt. Stain 


/> 




.03 




. 10 




A 


9.8 


2 


9 .7 


3 


B 


9 .6 


4 


9 .6 


4 


C 


9 .6 


4 


9 .6 


4 


D 


9.7 


3 


9.7 


3 



Burning. 

The cones were placed in cone pats with standard cones, and 
were fired to cone twelve. They stood this heat without the least 
melting, or deformation. 

The trial pieces of "body A were packed in powdered calcined 
flint in wadded saggers. The deformation "bars were placed on sharp 
edges six centimeters apart .also in wadded saggers. The saggers 
were put in the gas kiln and fired to cone twelve, which "brought 
cone eleven down inside the saggers. An oxydizing atmosphere 
prevailed throughout the burn, except for a heating up period at 
the start. 

The trial pieces of bodies B,C,and D were placed in cal- 
cined flint in wadded saggers. The bars were placed on sharp edges 
3ix centimeters apart, and also were placed in wadded saggers. The 
saggers were placed in a coal test kiln and fired to cone five 
in thirty hours. The cone3 were down inside the saggers. 

Burned Properties. 

The test pieces appeared as follows: 

The body A with three percent stain burned to an attract- 
ive pale green color. The piece was thoroughly vitrif ied , and 
burned without cracking or deforming. 



23 



The "body A with ten percent stain burned to a greener 
color than the other hut was not as attractive , and did not have 
as smooth a surface. Some blisters formed on the bottom of the 
piece. 

The body B with three percent color burned to a gray color 
with a pinkish tinge. The pieces were wholly unsatisfactory, 
although they burned without difficulty. 

The body B with ten percent color gave the same results. 

Both C bodies burned to a gray color with a greenish tint. 
A dirty greenish stain appeared around the top edges of the piece. 
The surface was poor, and the piece was not wholly vitrified. 

The body D with three percent stain gave a pale green 
color similar to that given by the body A. The color was a little 
more grayish, but very attractive. The piece was vitrified , and no 
trouble was had with cracking or blistering. 

Body D with ten percent color was impossible to cast. 

The body without the color burned with the same excellent 



properties as formerly. 



Burned Lengths. 



Body 




Amt . Stain 


% 


Amt . Stain 


of 

7° 






.03 




.10 




A 




6.2 


16 


8.35 


13 .5 


B 




8.0 


16 


8. 15 


15 


C 




8.1 


15 


8.4 


12 


D 




8.2 


15 






The 


total 


shrinkage wa3 


high , amounting to 


an average 


nteen 


and 


one half percent total. 


as against 


fourteen per 



cent total for the body alone. 



24 

The Deformations were as follows, 

The "bodies A were "bent one centimeters in six centimeters. 

The bodies B did not deform. 

The bodies C deformed one tenth of a centimeter in six . 

The bodies D deformed two tenths of a centimeter in six. 

y. SUMMARY OF RESULTS. 

The pink coloration was not developed at all. The green 
coloration was well developed in bodies A and D. Rone of thie 
colored bodies was translucent. The body D showed the be3t all 
around properties , such as good color, small deformat ion , and little 
shrinkage ,with a low cone. The body A when burned to cone five 
developed the best green color, but was not as thoroughly vitrified 
as the others. 

VI. GENERAL CONCLUSIONS. 

In the development of a belleek body, the points raised in 
the introduction , in regard to the properties of belleek, were all 
satisfied in the body B 7. 

Although a pale pink body was not developed , the pale green 
was satisfactory when color alone is considered. The pale green was 
almost a gray green in appearance. However, as far as investigated, 
introduction of even a small amount of color destroys the trans- 
lucency altogather. 

If further invest igation were to be done, the D body should 
be burned to cone eight instead of cone five .which might impart 
some translucency to it. 

The writer does not see how a pink color can be obtained, 
unless a good pink fritt can be produced which will retain the 

same color when added to the body. 



25 



VII. ACKMO^EDG'SMWT. 

The writer wishes to acknowledge his appreciation for 
the advice and assistance given by Professor Binns and 
Professor Parmelee during the preparation and performance 
of the work. 



